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Better Harvest, Better Crop on the Way?

Wednesday, September 17, 2003
filed under: Harvest/Storage

“Both aeration and natural air drying require a fan, but are as different as a garden tractor and a large four-wheel drive tractor.” – Ken Hellevang, NDSU extension ag engineer

As a rule of thumb, it’s good to see sunflower blooming in the Northern Plains by August 15, as was the case in many areas this growing season, says Curt Stern, field representative with ADM's Northern Sun at Enderlin, N.D.

“With a typical first killing frost around September 20, it gives fields then about a month of good crop maturing weather,” he says. Thus, the early bloom may hold promise for better harvest conditions and better quality—if weather cooperates.

“So far so good. We could have a much better quality crop going in the bin this year then what we’ve had the past few years, and that makes it easier to store, if that’s their preference,” says Stern. “The key is what moisture you’re take the crop off and putting it in the bin. You want to get that moisture down to around 10% after the crop comes off, and lower for longer-term storage.”

But don’t wait until it’s too dry.

“Seed size could suffer if gets too dry and heads shell out, with larger seeds tending to shell out first. So with seed size that could be a premium, take steps to preserve it,” says Dean Pedersen, Harvest States Sunflower (formerly Agway), Grandin, N.D.

For best quality sunflower, start harvest when moisture levels are in the mid teens, and then dry quickly. It is important not to allow seed moisture to become too low (sunflower in the High Plains is particularly sensitive to this), which may result in more hull damage at harvest. The greater the hull damage, the more susceptibility of fungal infection in the seeds. Research has shown that harvesting with seed moistures of 5 - 7% resulted in 15 -18% hull damage, where as harvesting seed with a moisture of 9% resulted in less than 10% hull damage.

Tim Petry is optimistic that harvest conditions will be better this year. “Last fall was a challenge around here for really all row crops. There was no opportunity to air dry anything. Drier conditions also aren’t conducive to Sclerotinia head rot.”

Petry, field production manager for Dahlgren & Company, Crookston, Minn., is hopeful that an early harvest will give producers more time to focus on preharvest storage preparation and post-harvest management. “More growers are precleaning before putting the crop in storage or drying it; getting rid of fines and dockage, which will give you safer drying and better conditions to store the crop.”

Some growers also apply bin treatments to control insects. There are “crack and crevice” type treatments on the market, including products labeled for sunflower. One such product is “Insecto,” made from diatomaceous earth. The non-chemical insecticide is a fine, dry dust which attaches to adult and larvae insects as they crawl through treated grain and dusted bins, and the insects die from dehydration within 1-14 days after exposure. An aeration fan blows the product into an empty bin; treatment time takes minutes, inexpensively.

Distributors include UAP (formerly Ostlund Chemical), and Cenex Land O’Lakes in the Northern Plains, and Better Crops, Cenex LOL, and Hi-Plains Co-op in the High Plains. More information about the product can be found online, Sunflower growers, particularly confection, should consult with agronomists before applying storage treatment products.

Ken Hellevang, extension engineer at North Dakota State University, says “getting air on the bin” is a common reference to aeration and natural air drying, but can be confusing in distinguishing the post-harvest management practices.

Both require a fan, but are as different as a garden tractor and a large four wheel drive tractor. Drying requires an entirely different system than aeration, just like pulling a 60 ft. tillage implement. Just like we cannot say any tractor is OK for pulling a tillage

implement, not just any fan can properly dry grain.”

Cooling sunflower requires less airflow than drying sunflower to remove moisture. “Sunflower is a fairly light product compared to other grains, such as wheat. It takes very little airflow to change the temperature of sunflower,” says Hellevang. “But when it comes to removing moisture content with drying, it takes a lot of air flow. It requires an adequate drying system. I like to see air flow of at least ¾ cfm (cubic ft of air/minute) per bu for adequate drying. That allows you to handle up to about 15% moisture. Unless you have that kind of airflow, the drying time becomes inadequate.”

It makes good economic sense to take steps to preserve the quality of sunflower going into storage, especially so for confection, says Petry. “You’re looking at a $5 to $6 hit when you go from an edible product to a bird food product. That’s all the margin and then some in producing the crop. The cost of keeping the product in shape gets minimized quite a bit when you consider what your economic loss could be if it isn’t managed properly.” —Tracy Sayler

Drying oilseed sunflower in October

(47° F and 65% relative humidity)


Fan Time

Moisture Airflow -----------

Content (cfm/bu) hours days


17% 1.00 648 27

15% 1.00 480 20

0.75 720 30

0.50 960 40

13% 1.00 336 14

0.75 504 21

0.50 672 28


Add enough heat when needed to dry

sunflower to a safe storage

moisture content. Generally enough

heat to warm this air 10 degrees is

the maximum amount required. As a

rule of thumb, about 2 kw of heater

will be required per fan motor


See NDSU Extension Service circular

AE-701 Grain Drying for more information

on drying sunflower and other grain. It can

be found online at

See more articles on drying and storing sunflower online at Click on the link “Especially for Producers,” “magazine,” then “the archives.” See topics under “Harvest/Storage.”

Estimate Cost for On-farm Storage

The Kansas State University Extension Service offers a free spreadsheet to help estimate on-farm storage costs, online at

More online resources for postharvest grain storage tips and information:

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